The 29-year-old explained on BBC Radio Ulster's Stephen Nolan Show yesterday that he was examined, treated and then sent home but later became ill.

"I was seen after a wait and I then developed a headache and started vomiting quite severely. I was talking about seven to eight times a day. I think at one sitting I was sick 12 times, which was a bit horrific. The bedroom was a complete mess."

He said he felt so bad he realised he must be suffering from bad concussion.

"It was that rough it was horrible. I had to go back to A&E. This time my mum took me and I got a CT scan and after that was done a junior doctor came and took me into a little side room just to discuss the CT scan results.

"I just kept thinking, well, there must be some sort of complication," he said.

"She sat me down to give me my results, and on a secondary pick-up they had seen I had brain ischemia and I had brain damage to both frontal lobes, she told me I had brain damage."

He said he went into shock when he heard the doctor tell him the news.

"They said it was unusual for someone my age to have that condition. I went out and told my mum and you could see the shock in her face as well.

"Then the reality set in and I thought, I'm 29 with brain damage, what does this mean? Are my parents going to have to look after me? All those thoughts creep in."

Mum Anna then drove him back to her house in Magherafelt.

"We sat down and had a chat, then I get a phone call telling me there was a mix-up and that I'm actually in the clear. They had mixed up my scan with that of an 80-year-old woman who was actually in front of me in the queue for a CT scan. She had her head heavily bandaged.

"My mum just broke down with relief," he added

Mr York said he did not blame the doctors.

"I would never blame the NHS, the staff have never been anything but professional and competent. But the fact that they're working under those conditions and that pressure that it can lead to those mistakes."

A Northern Trust statement said:"We can confirm that an error relating to a scan occurred on his second attendance at the emergency department and we apologise for the distress this caused to Mr York and his family. The doctor treating Mr York quickly spotted the error and contacted him within 30 minutes of leaving the hospital."